INTRACELLULAR MICROELECTRODE STUDIES OF ANTIDROMIC RESPONSES IN CORTICAL PYRAMIDAL TRACT NEURONS

Abstract

Antidromic spikes and transmembrane potential changes of short latency have been recorded in 72 pyramidal tract neurons in the cat. Inhibitory (polarizing) post synaptic potentials, with or without spikes, with a mean latency of 3.9 msec. and duration of over 100 msec. as compared to a mean spike latency of 1.4 msec. Shorter latency (3.2 msec.) excitatory (depolarizing) post synaptic potentials were recorded of briefer duration. After potentials were also identified in some cells as distinct from inhibitory and excitatory post synaptic potentials. It is concluded that axon collateral inhibition and excitation mediated by cortical interneurons, are both important in the control and integration of motor function in the corticopyramidal system of the cat.